Add static field to set custom Sdk version

This is to be accessed from user or library code when running inside
Studio. That will be used instead of the SDK_INT version coming from
layoutlib.

Bug: 250806506
Test: N/A
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:42294a5111ae4ee6a788865b9b286d197a0971c8)
Merged-In: I8527e918569f5b60102ba2f6bbae4789ba01f17a
Change-Id: I8527e918569f5b60102ba2f6bbae4789ba01f17a
2 files changed